|Table 2: Comparison of nonimaging modalities in the detection of intracranial stenosis.|
|CDDI: Color Doppler-assisted duplex imaging, PFI: power-flow imaging. |
*Data are percentages using DSA as the reference standard.
‡North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria were used for stenosis calculations: , where is normal diameter and is stenosed diameter. NASCET stenoses were grouped according to the following grading scale: normal (0%–9%), mild (10%–29%), moderate (30%–69%), severe (70%–99%), or occluded (no flow detected). Normal (0%–9%) and mild (10%–29%) stenosis were not considered diseased vessel segments and were excluded from analysis.
†Ultrasound emission energy and gain cannot be increased high enough without the appearance of disturbing acoustic noise that diminishes the reliable depiction of orthograde flow signals.